smart-matching and sub funhouse
Bad timing: now that smart-matching is under scrutiny, I've started to have fun writing Perl like this:
use signatures;
use Path::Class;
file( 'file.txt' ) ~~ sub ($f) {
say $f->basename;
say $f->slurp;
};
This style and syntax is reminiscent of Python's with and Ruby's do, and, for this use case in particular, feels a bit more natural to me than right-to-left, functional-style Perl5:
map { say $_->slurp } file( 'file.txt');
I was just wondering if anyone likes them Perl served like tha'.
Thinking of an alternative, but similar syntax, a year or so ago I forked Perl 5.13.x and patched it trying to make it take sub { } as a method call. Things didn't work as I expected as I'm a Perl5 internals noob, it was a really hot Madrid summer afternoon and I had a higher-than-usual dead brain cell count, but the idea was to be able to call closures on objects:
my $f = file( 'ah-ha' );
$f -> sub {
say $_->basename . ' = ' . $_->slurp;
};
Which probably could work nicely on native types too:
( 1..10 ) -> sub { ... }; # same as sub{ ... }->( 1..10 );
@arr -> sub { ... }; # sub{ ... }->( @arr );
%hash -> sub { ... };
"string" -> sub { ... };
The insignificant white-space before and after the arrow makes it even more expressive.
This is not a proposal, Perl6 already that covered: 'ponty-blocks' come to mind, which even drops sub altogether. But it sure feels like something that could make quite easily into Perl5 without causing a lot of grief.
Perl and all things considered
None of that feels Perlish to me.
You can already call subs as methods, but to avoid confusion with a method called "sub", you need to wrap them in a scalar deref:
file('file.txt')->${\sub ($f) { say $f->slurp; }};Although you could perform this in Perl 6:
This would be more Perl6ish and similar to Aristotle's Perl 5 example:
Or even this:
I should note though that those examples are just for comparison. If you actually only have a single method call in your block and aren't performing exception handling, it's much simpler:
say open('file.txt').slurp;